/Engine/Plugins/Developer/Concert/ConcertMain/Source/Concert/Public/IConcertSession.h
Register a custom request handler for this session
void InternalRegisterCustomRequestHandler ( const [FName](API\Runtime\Core\UObject\FName) & RequestMessageType, const [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [IConcertSessionCustomRequestHandler](API\Plugins\Concert\IConcertSessionCustomRequestHand-) > & Handler )